kbfsfuse: enable mdv3 for kbfsdocker tests
kbfsfuse: enable mdv3 for kbfsdocker tests

Issue: KBFS-2228

keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/kbfs,keybase/client,keybase/kbfs,keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/client,keybase/client